As you say, the double Xi is correct for the wedding. A number of proofreaders who are Chinese missed this, but the mix-up is mine; mea culpa.In the sense it appears in the story, luck and fortune are synonyms. The antonym for good luck is bad luck, or bad fortune (thesaurus.com).

The Chinese character has different meaning when it uses in different places and occasions.

When “FU” is pasted on the door and entrant of the room, it means good fortune. “FU” consists of four different Chinese characters; clothes, roof, mouth and farming land. When a family has clothes to wear, house to live, food to eat and land to farming, the family is considered to have good fortune.

The Chinese character has different meaning when it uses in different places and occasions.

When “FU” is pasted on the door and entrant of the room, it means good fortune. “FU” consists of four different Chinese characters; clothes, roof, mouth and farming land. When a family has clothes to wear, house to live, food to eat and land to farming, the family is considered to have good fortune.

The Chinese character has different meaning when it uses in different places and occasions.

When “FU” is pasted on the door and entrant of the room, it means good fortune. “FU” consists of four different Chinese characters; clothes, roof, mouth and farming land. When a family has clothes to wear, house to live, food to eat and land to farming, the family is considered to have good fortune.

The Chinese character has different meaning when it uses in different places and occasions.

When “FU” is pasted on the door and entrant of the room, it means good fortune. “FU” consists of four different Chinese characters; clothes, roof, mouth and farming land. When a family has clothes to wear, house to live, food to eat and land to farming, the family is considered to have good fortune.

Great explanation, thanks.

Here are three versions of the Fu character painted by Chinese Mint workers to welcome this year's Spring Festival (together with the 3 Yuan silver Fu coin for 2017). Hundreds of these were posted that day.